foo.cpp: In function 'int main()':
foo.cpp:10:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if(n>=0 && n<0x80000000 && x>=0 && x<=9) break;
                      ^
foo.cpp:14:30: error: 'itoa' was not declared in this scope
         ln=strlen(itoa(i,a,10));
                              ^
foo.cpp:14:31: error: 'strlen' was not declared in this scope
         ln=strlen(itoa(i,a,10));
                               ^